PCT International Publication No. WO 89/04829, U.S. Pat. No. 5,039,676, and PCT International Publication No. WO 93/09114 disclose substituted tetrahydrofuran azole compounds having utility as antifungal agents. A number of processes for the synthesis of these compounds are known. In addition, U.S. Ser. No. 08/055,268 describes a process for preparing chiral intermediates for use in the preparation of these antifungal agents. Dialkylmalonate derivatives of the formula IV ##STR2## wherein R is C.sub.1 -C.sub.6 alkyl, are important intermediates used in this process. An efficient synthesis of compounds of the formula IV is therefore a key factor in the synthesis of antifungal compounds via this process.
Preparation of compounds of the formula IV is most readily accomplished by the process described in U.S. Ser. No. 08/055,268. This process, as shown in Reaction 1, comprises reacting a dialkyl malonate anion, wherein M.sup.+ is a suitable metal counterion and R is C.sub.1 -C.sub.6 alkyl, with a compound of the formula V, wherein Z is a leaving group selected from Br, --OSO.sub.2 CH.sub.3 or --OSO.sub.2 C.sub.6 H.sub.4 CH.sub.3, to form a compound of formula IV. However, the prior an methods for preparing ##STR3## compounds of the formula V are typically low yielding, inefficient and not amenable to commercial scale synthesis. It is therefore desirable to develop a chemically efficient, high yield process for the synthesis of compounds of the formula V.